Diagnostic performance of native T1 in grading histologically proven myocardial glycosphingolipid accumulation in Fabry disease

OBJECTIVE: Fabry disease cardiomyopathy (FD-CM) is a genetic disorder induced by glycosphingolipid accumulation (GSL-A) in cardiac cells, resulting in left ventricular hypertrophy (LVH) and contractile impairment. Native T1 (nT1) mapping by cardiac magnetic resonance (CMR) effectively detects myocardial GSL-A in patients with FD-CM. However, the association between nT1 values and GSL-A severity has not been histologically confirmed. This study aims to assess the capability of nT1 to classify GSL-A burden, using endomyocardial biopsy (EMB) as the reference, and to identify the best matching site for nT1 measurement. MATERIALS AND METHODS: Forty FD-CM subjects undergone CMR and EMB were classified into 4 groups according to GSL-A severity. CMRs were performed using a comprehensive protocol including nT1 and T2 mapping sequences. Global, per-plane, and septal segmental myocardial nT1 and T2 values (excluding late gadolinium enhanced areas) were compared among groups. Correlations between nT1 values, GSL-A and LVH were explored. Statistical analyses used distribution-appropriate tests, including group comparisons, correlation, and ROC analyses. RESULTS: Significant nT1 differences emerged among groups at all measurement sites, with significant negative correlations with GSL-A, particularly in AHA segment 9, the mid-interventricular septum region of interest and midventricular plane (r = -0.741; -0.716; -0.715; p < 0.001). nT1 measured at these locations demonstrated excellent diagnostic accuracy in identifying severe GSL-A (area under the curve: 0.860, 0.903, and 0.895, respectively). CONCLUSION: Myocardial nT1 values strongly correlate with GSL-A, with midventricular septum measurements providing the best agreement. If supported by further studies, CMR could act as a noninvasive tool for disease staging and risk stratification, helping to identify patients in advanced, higher-risk stages. CRITICAL RELEVANCE STATEMENT: Native T1 mapping correlates closely with histological glycosphingolipid accumulation in Fabry cardiomyopathy. This noninvasive biomarker may support early disease stratification and guide timely therapeutic intervention. KEY POINTS: Native T1 values are a valid biomarker of glycosphingolipid accumulation in myocardial tissue and correlate with accumulation degree. Midventricular interventricular septum is the preferred site for nT1 measurement, showing the best agreement with glycosphingolipid accumulation at endomyocardial biopsy. The use of native T1 in the setting of suspected cardiac Fabry disease will help to stratify disease severity, without the intrinsic risk of endomyocardial biopsy.